Funds are requested for purchase of a high field NMR spectrometer for observation of 1H and 13C nuclei to determine structures of complex low molecular weight compounds (Mr Less than 6,000) and to characterize protein ligand interactions. Studies are proposed directed toward determination of the possible relationship between the structure of the carbohydrate side chains of human fibrinogen and its concentration in plasma in individuals with normal and inherited abnormal fibrinogens. The NMR will also be used to determine the structure of glycopeptides obtained from cell surface proteins, as well as to determine the structure of laboratory synthesized cofactors, cofactor analogs, oligosaccharides, and substrates of enzymically catalyzed reactions. Attempts will be made to determine the ionization behavior of imidazole and other groups in peptides and proteins from measurements of the pH dependence of 1H and 13C resonances. Some of these studies are directed toward characterization of imidazolium thiolate ion pair interactions which appear to be important for the activity of several proteins. Additionally the instrument will be used to determine thermodynamic and kinetic parameters for the binding of carbohydrates to lectins. Nuclear Overhauser effects and transfer of nuclear Overhauser effects will be studied in attempts to characterize alterations in ligand conformation upon their binding to protein, the relative disposition of FAD and NAD+, in lipoamide dehydrogenase and glutathione reductase, as well as to determine the orientation of enzyme bound substrate analogs with respect to pyridoxal phosphate in D-serine dehydratase. Attempts also will be made to determine the structure of stabilized enzyme bound cofactor intermediates in an effort to establish reaction pathways for folate, pyridoxal phosphate and flavin requi0ing enzymes. Additionally the spectrometer will be used to determine the structure of products and monitor the progress of enzymically catalyzed reactions where other methods of analysis are not feasible.